Role of micronutrient in crops

1. ROLE OF MICRONUTRIENT IN
CROPS
• G

2. N K Ca Mg P S
macronutrients micronutrientsair & water
Soil
~ 18 elements have been
identified as essential for
the growth of all plants
C OH Cl Fe Mn Zn B Cu Mo
Na
Co
Si
V Ni
Needed by
some plants
0.1%

3. CRITERION FOR
ESSENTIALITY OF NUTRIENT
• According to Arnon:-
1.In the absence of nutrient plant should
not complete its life cycle or set the seeds.
2.Element must be directly involved in the
metabolism of plant.
3.Requirement should be specific and non
replaceable.

4. • Those nutrients that are needed in smaller amounts by
the plants, but are still essential to plant growth are
called micronutrients. The micronutrients are boron
(B), copper (Cu), chlorine (Cl), iron (Fe), manganese
(Mn), molybdenum (Mo), and zinc (Zn).

5. – B. Plant growth, fueled by cellular respiration, takes
place primarily at night when photosynthesis is shut
down. With signals from hormones, enzymes are
produced. Each enzyme has a specific job. The
enzymes break down sugars and recombine them
with nitrogen and other nutrients. Many complex
products result including, starches, pectin, lignin,
cellulose, lipids or fats, proteins, pigments,
hormones, vitamins, and alkaloids and tannins that
protect plants from pests and diseases.

6. Some elements (e.g. Se, I, As, Cr)
have been identified as essential for
animals but not for plants.
Boron is the only element that has been
identified as essential for plants
but not for animals

7. Co2+
Inorganic nutrient forms taken up by plants

8. Micronutrients have very important roles in plant metabolism

9. Micronutrient deficiency
symptoms tend to show
up on new leaves
Nutrients used in
abundance tend to be
easily moved around
Negative
interactions

10. 6.5 7.5

11. soil tests for micronutrients
have limited value
•sampling and soil test methods are less reliable
•calibration databases are inadequate
Plant tissue levels of micronutrients
often provide a better indication of
micronutrient needs than soil test
results
Unfortunately

12. http://iah.aces.uiuc.edu/pdf/Agronomy_HB/11chapter.pdf
Critical tissue nutrient levels for corn, soybeans and alfalfa
Lower nutrient levels in designated plant tissue
indicates that nutrient deficiency is likely.

13. Micronutrients deficiencies are normally
associated with one or more of the following
five situations:
(1)highly weathered soils
(2)coarse-textured soils
(3)high-pH soils
(4)Organic/muck soils
(5)soils that are low in organic matter because
erosion or land-shaping processes have removed
the topsoil.
If one or of these situations applies and soil test
levels and/or plant tissue levels are low, evaluation
of micronutrient fertilizers is recommended.

14. BORON
• A. The exact role of boron is unclear, but it
appears to be essential for pollination and
reproduction, cell division, and the transport of
sugars.
• SYMPTOMS:-
• Young leaves look yellow and thick when the
nutrient is lacking, internodes are shorter.
• Drop of buds, flowers and developing fruits is
also typical symptoms.

16. Boron (B) deficiency is a common occurrence on alfalfa. Characteristic
symptoms of the deficiency are yellowing of the upper leaves, eventually
turning to a purpling color, along with stunting of the upper stems. Deficiency
symptoms for B are similar to leaf hopper damage. Deficiency symptoms are
most commonly observed during drought conditions. If B deficiency has
previously been observed, it will likely occur whenever alfalfa is grown in that
field unless B is applied on an annual basis.

17. NCDA recommendations for Boron:
all brassicas: 2 lbs per acre
cantaloupes & cukes: 1 lb per acre
peppers and tomatoes: 1 lb per acre
okra: 0.5 lbs per acre
Foliar application of Boron
Crops with high demand for boron may
benefit from foliar applications of
boron (~ 0.2 lbs B/acre) at the
following times: prior to heading of
cole crops, prior to root swell in root
crops, and at first bloom for tomatoes
and okra.
Adequate boron nutrition is
critical for high quality
vegetable crops

18. MANGANESE
• Manganese is important in chlorophyll
formation. It is part of enzymes involved in
respiration and nitrogen metabolism.
• Symptom:-
• Interveinal chlorosis of young leaves, no
sharp distinction between vein and
interveinal areas.
• Development of interveinal white streaks in
wheat.

19. Manganese deficiency (stunted plants with green veins in yellow or
whitish leaves) is common on high pH (alkaline) sandy soils,
especially during cool, wet weather in late May and June.
Suggested treatment is to spray either manganese sulfate or a
manganese chelate complex onto the leaves soon after the
symptoms first appear. Broadcast soil applications of Mn are often
ineffective because the Mn becomes unavailable.

20. Iron is important in chlorophyll formation
and is component of enzymes involved in
photosynthesis, respiration, and nitrogen fixation.
Symptoms:-
-Interveinal chlorosis of young leaves.
-Twig dieback.
-In severe cases, death of entire limbs or plants.
IRON

22. Soybeans normally outgrow the stunted, yellow appearance
of Fe chlorosis. As a result, it has been difficult to measure
yield losses or decide whether or how to treat affected
areas.
Research in Minnesota has shown that timing of Fe
application is critical to attaining a response. Researchers
recommend that 0.15 lb/acre of iron as iron chelate be
applied to foliage within 3 to 7 days after chlorosis
symptoms develop (usually in the second-trifoliate stage of
growth). Waiting for soybeans to grow to the fourth- or fifth-
trifoliate stage before applying iron resulted in no yield
increase.

23. MOLYBDENUM
• F. Molybdenum is part of enzymes involved in
nitrogen metabolism. It aids nitrogen fixation and
protein synthesis.
• Symptoms :-
• yellow older leaves and growth is stunted.
• Marginal scorching and cupping or rolling of
leaves.
• Veins remain green producing a mottled
appearance.

25. Molybdenum
Molybdenum (Mo) differs from most of the other
micronutrients in that it increases in availability with an
increase in pH.
The deficiency is limited almost exclusively to legumes,
including soybeans grown on very acidic soils (pH< 5.0).
In nearly all cases, it is more economical to apply limestone
to correct the problem than to apply Mo. However, if you
must grow soybeans on very acidic soils, be sure to use a
seed treatment that includes molybdenum.
Soil pH is the only soil test that detects the potential for Mo
deficiency.

26. -Zinc is important in chlorophyll, auxin, and starch
formation, and it is part of the enzymes that are
involved in respiration.
--Symptoms:-
-Reduced fruit bud formation.
-Dieback of twigs after the first year.
-Striping or banding on corn leaves.
-Shortening of internodes.
ZINC

27. Zinc
zinc (Zn) deficiency, while not common in , is much
more likely to occur on corn than on soybean.
Documented response to Zn has been limited to low
organic matter soils and sandy soils in northwestern
Illinois.
High pH (greater than 7.3) and very high P levels
increase the likelihood of Zn deficiency. If high P
levels have resulted from manure applications, Zn
deficiency is unlikely.
Soil test levels of Zn are poor indicators of yield
response to the application of Zn.

28. Zinc deficiency in corn is exhibited on the upper leaves
as interveinal chlorosis. The veins, midrib and leaf
margin remain green. As the deficiency intensifies “feather
like” bands develop on either side of the midrib and the
leaves may turn almost white (hence the term “white bud”
was coined to describe Zn deficient corn plants); internodes
are short resulting in stunted plants.

30. CHLORINE
• C. Chlorine is involved in light reactions of
photosynthesis. It aids root and shoot
growth.
• Deficiency:-
• Wilting followed by chlorosis.
• Bronzing of leaves.
• Excessive branching of lateral roots.
• Chlorosis and necrosis in tomatoes and
barley.

32. COPPER
• Copper regulates several chemical
processes including chlorophyll synthesis
and respiration.
• SYMPTOMS:-
• yellowing of leaves with the younger
leaves affected first.
• Bark of tree is rough and blistered.
• Stunted growth,flowering and fruiting may
fail to develop in annual plants.

34. Summary:-
None of the micronutrient soil tests are very
reliable for predicting crop response to
fertilization.
If soil test levels are high, the likelihood of response to fertilization
is very low. If soil test levels are low to medium, the potential for
response to the applied element may be high, or it may be low.
Decisions about micronutrient fertilization should take into
account the sensitivity of the crop to be grown, soil characteristics
that affect the availability of the element, such as soil pH, organic
matter, soil texture, and soil P level, soil test levels and tissue test
levels.
If multiple factors indicate potential for deficiency,
fertilization on a trial basis is probably a good risk.

35. Mn, B and Cl help crops to resist fungal pathogens
Chloride (Cl), usually in the form of potassium chloride (KCl), has been
shown to reduce the severity of some fungal diseases.
Adequate Mn nutrition reduces the incidence of foliar disease in most
crops. Mn is needed for the synthesis of lignin and phenols,
compounds used by plants to combat infection by pathogens.
Boron (B) deficiency has been linked to the production of small fissures
and cracks that may be the initial entrances for fungal pathogens.

37. Micronutrient Malnutrition
 Affects nearly half the world’s population
 More than 840 million people cannot meet
their basic daily food and nutritional needs
 About 2 billion people, mostly women and
children, are at risk from diseases, premature
death, and lower quality of life linked to
deficiencies of vitamin A, iodine, and iron